Fix Incorrect Trust Agent Count

The total number of trustagents can still be incorrect if the user
enables a trustagent, and then the trust agent component gets disabled,
since the user does not manually toggle the preference themselves. Fixed
by switching back to the original method of using TrustAgentManager, but
also pass a flag that allows us to choose on whether we want to filter
the trustagents based on whether it has an activity (which not all
trustagents are guaranteed to have).

Bug: 240969157
Test: Local test + atest
Change-Id: I5106859f61ddf36c1bf008da18be889ceaf27a8d